Experimental study of electron transpiration cooling with a 2-kW laser heating system

Bak, Junhwi; Rekhy, Anuj; Limbach, Christopher; Miles, Richard B.; Creel, James

doi:10.2514/6.2022-0983

Cited by 6 publications

(1 citation statement)

References 30 publications

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“…Figure 10 shows three experimental cases reflecting the thermal and current effects of the on/off control of ETC. These data were obtained in a manner similar to that used in [60]. After the cathode is heated to a preliminary steady state condition, an additional stepwise increase in the heating laser power, ∆P L ≈ 640 W, is applied at t = 0 s. The top figure shows the temporal evolution of surface temperature, and the bottom figure shows the total collected current.…”

Section: Time-resolved Observation Of Surface Electron Emission Coolingmentioning

confidence: 99%

Quantification of plasma enabled surface cooling by electron emission from high temperature materials

Bak,

Tropina,

Creel

et al. 2024

Plasma Sources Sci. Technol.

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In this work, the potential for hypersonic leading edge cooling by electron emission is demonstrated. To overcome space charge limitations the experiments are carried out in an argon discharge at 1 Torr. Cooling is observed with time-resolved measurements of the electron emission current and surface temperature, taking advantage of well controlled laser heating of the emitting surface and time accurate surface pyrometry. For the ignited mode of the plasma discharge, surface cooling by the electron emission is directly observed, leading to an estimated cooling rate of 1.6±0.2 MW/m2. Higher cooling rates with self sustained plasmas for space charge mitigation are expected using cesium transpiration. A two-dimensional model of heat transfer has been developed, which reproduces well the experimentally observed cooling dynamics. Parametric tests of emitter materials with various work functions show that for effective surface cooling by electron emission, the optimal work function must be less than 3.0 eV. This result indicates that electron cooling can be a promising thermal protection method for leading edges of hypersonic vehicles in flight.

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Section: Time-resolved Observation Of Surface Electron Emission Coolingmentioning

confidence: 99%